講演情報
[20p-C501-12]Current direction dependent transverse signal in topological insulator/ferromagnet heterostructures
〇(M1)Yuxiang Mao1, Masamitsu Hayashi1, Masashi Kawaguchi1, Shunzhen Wang1 (1.The Univ. of Tokyo)
キーワード：
topological insulator、transport、nonreciprocal effect
Spin currents are central to spintronics since they are the handle to manipulate magnetization in thin film nanostructures. The transport properties of spin current in normal metal/ferromagnet (NM/FM) bilayers have been under study given the interest in spin orbit torque devices using such structures. Studies of the spin Hall magnetoresistance (SMR) and the unidirectional spin Hall magnetoresistance (USMR) have been extended to other systems that include topological insulators and Dirac/Weyl semimetals. Recently, an USMR-like magnetoresistance was observed in topological insulator/ferromagnet (TI/FM) heterostructures. Significant interaction between the topological surface states and spin current in such structures have been reported.
In this work, we investigate the linear and nonlinear Hall signals in TI/FM heterostructure. Molecular beam epitaxy (MBE) was used to form the topological insulator thin films. The growth was monitored by reflection high-energy electron diffraction (RHEED). RF magnetron sputtering was used to form the ferromagnetic layer. The films were subsequently fabricated into Hall bar devices using conventional lift-off process. In the measurement, an alternating current (AC) was applied to the sample. The devices were tested in a cryostat. A lock-in amplifier was used to measure the first and second harmonic voltages. Both the first and second order signals show significant dependence on the current direction. In the presentation, we discuss the experimental results in detail.
In this work, we investigate the linear and nonlinear Hall signals in TI/FM heterostructure. Molecular beam epitaxy (MBE) was used to form the topological insulator thin films. The growth was monitored by reflection high-energy electron diffraction (RHEED). RF magnetron sputtering was used to form the ferromagnetic layer. The films were subsequently fabricated into Hall bar devices using conventional lift-off process. In the measurement, an alternating current (AC) was applied to the sample. The devices were tested in a cryostat. A lock-in amplifier was used to measure the first and second harmonic voltages. Both the first and second order signals show significant dependence on the current direction. In the presentation, we discuss the experimental results in detail.